The invention relates to a short arc discharge lamp provided therein with a mirror.
One type of a short arc discharge lamp (hereinafter simply referred to as a “discharge lamp”) is known in which a mirror is provided therein. Such a discharge lamp includes a lamp body (hereinafter simply referred to as a “body”) formed of an opaque insulating member and including therein a reflection surface curved in a concave shape, and only a portion where light is to be extracted is formed of a translucent member. For example, reference is made to Japanese Unexamined Patent Application Publication No. 2013-016361.
Referring to FIG. 5, an exemplary discharge lamp provided therein with a mirror has a body 30 and a window member 40. The body 30 includes therein a reflection surface 31 curved in a concave shape, and the window member 40 covers a front opening of the body 30. The reflection surface 31 defines discharge space S surrounded by the reflection surface 31 and in which a cathode 32 and an anode 33 are disposed to oppose each other.
In FIG. 5, reference numerals 34, 35, 36, 37, 38, 39, and 41 denote a conductive supporting member, a metal block, a ceramic spacer ring, a metal ring that serves to supply power to the cathode 32, a first metal tubular body, a second metal tubular body, and a window supporting member, respectively.
In general, the reflection surface in the body of the discharge lamp is parabolic or the like in cross-sectional shape, and is disposed such that a focal point thereof is located at a gap between the cathode and the anode.